In Puppeteer, you can close the browser instance by calling the browser.close() method. Here is an example:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
// do something
await browser.close();
})();
In this example, we first launch a new browser instance using puppeteer.launch(), and then create a new page. After performing any necessary actions on the page, we call browser.close() to close the browser instance.